Is this a Life and Death feature or bug?
My sim self's wife Luna was at the end of the young adult life stage. She had a birthday, blew out the candles and aged up. One sim week later, i noticed this: She still is displayed as Young Adult ...
Forum Discussion
It may just have been a bug that happened just at that time. Perhaps try testing by aging her up, then see if the correct age is shown with her name. If it is, then you can age her back down to the adult age again.
